1. Field of the Invention
The present invention relates to a system for recovering motor function after spinal cord injury, by subjecting a patient to electrostatic field.
2. Related Arts
The spiral cord injury has often been seen in athletes"" injury and victims of car accidents. Since the patients are sometimes paralyzed and require a life-long care, a method of enhancing the motor recovery has been strongly desired. While biochemical and molecular biological approaches have been vigorously tried, but a study to find physical means to enhance the motor function recovery has been delayed.
Borgens, R. B. et al. report to the effect that completely severed spinal cord of a lamprey was regenerated in 2 months by application of 10 xcexcA of DC current across the severed section [xe2x80x9cSciencexe2x80x9d, Vol. 213, pages 611-617 (1981)]. They described that the electric current had a direct effect on the nerve regeneration, but the molecular mechanism has not been elucidated.
In Japan, health benefits of high-voltage electrostatic fields have been known, and several commercial devices to produce such a field have been proposed and sold in the market for the past decades. According to such a device, the electrostatic field has been caused on a single layer sheet or mat of a synthetic resin material such as polyvinyl chloride by applying DC voltage of several hundreds to several thousands to the mat. It has been said that these mats are effective for patients with muscle pain, arthritis and certain chronic diseases.
However, the device utilizing static electricity requires incidental facilities for increasing voltage such as a transformer, so that it becomes larger in size to increase manufacturing and running costs. Further, the device has a serious disadvantage of that a user might get a shock of electricity due to leakage thereof.
In order to overcome the disadvantages of the device utilizing static electricity, one of the researchers in the assignee company has studied to find facts that static electricity can be stably induced, if laminating a first sheet of conductive or semi-conductive layer having a volume resistivity of less than 104 xcexa9xc2x7cm to a second sheet of conductive or insulation layer having a volume resistivity of 104-1012 xcexa9xc2x7cm, and applying voltage to the first sheet, that a value of electrostatic voltage can be made higher level, if the difference in volume resistivity of the first and second sheets is set to 104 xcexa9xc2x7cm or more, and that a possibility of the dangerous shock due to leakage of electricity can be avoided by setting voltage and current to be applied to the first sheet to 25-800 VDC and 0.8 mA, respectively. The assignee company has filed a patent application in Japan on the invention, based on such findings [Japanese Patent 8-224316(A)]. According to the device disclosed in the specification for the Japanese patent application, it is possible to induce electrostatic voltage of xe2x88x923.05KV on the second sheet having a volume resistivity of 107 xcexa9xc2x7cm by applying 800 VDC to the first sheet having a volume resistivity of 103 xcexa9xc2x7cm, and this device is suitable for relieving headache and shoulder stiffness as well as preventing and curing insomnia and chronic constipation.
However, the uses of relieving headache and shoulder stiffness as well as preventing and curing insomnia and chronic constipation are not definite and it is difficult to confirm a concrete utility of such a device, since an effect of spiritual security giving to the user of the device cannot be neglected on generation of the utility.
By using the device, one of the inventors have energetically studied and investigated on influence(s) of the static electricity to a living body through tests using experimental animals to seek a new applicable use(s) of it. As a result, it has been unexpectedly found that the device is useful for inhibiting a decrease in an amount of bone to prevent and cure osteoporosis and also inhibiting an appetite without increasing a body weight to prevent and cure obesity. The related patent application was filed in Japan in the name of assignee company [Japanese Patent 9-322944(A) which corresponds to U.S. Pat. No. 5,836,997].
The inventors have further studied on influence of the static electricity to a living body through tests using experimental animals to find that the application of electrostatic fields effects on the recovery of rat spinal cord injury produced by a weight drop impulse on the exposed cord, so that the invention was established.
Therefore, an object of the invention is to provide a system for recovering motor function after spinal cord injury by putting a body of patient in an electrostatic field, for instance contacting his body with a mat which is inducing static electricity.
According to the invention, the object is attained by a system for recovering the motor function after spinal cord injury, which comprises a mat essentially consisting of a first sheet made from a semi-conductive or insulating material and having a volume resistivity of less than 104 xcexa9xc2x7cm and a second sheet made from a semi-conductive or insulating material, laminated on said first sheet and having a volume resistivity of 104 xcexa9xc2x7cm or more; an electric power source having an electrical circuit to apply 25-800 VDC to said first sheet; and a control unit for said electric power source.
The first and second sheets are made from one of silicone rubber, natural rubber, nitril rubber and synthetic resin material (such as polyvinyl chloride and polyurethane resin) and carbon.
It is preferable to set the electrical input to the first sheet as 800 VDC and 0.8 mA.